Door hold open attachment for a door check

ABSTRACT

An attachment for a conventional, surface mounted, overhead door control incorporating electrically actuated provision for holding the door open to any desired degree, but defeatable by manual pressure or by deenergization of the electric circuitry.

Unite States Patent n 1 Slayhaugh I [4 1 Dec. 10, 1974 DOOR HOLD OPEN ATTACHMENT FOR A DOOR CHECK [75] Inventor: Loren E. Slaybaugh, Arlington Heights, 111.

[22] Filed: July 28, 1972 [21] Appl. No.: 276,122

[52] US. Cl l6/48.5, 251/141, 16/62, 16/51 [51] Int. Cl. E05f 15/20 [58] Field of Search 16/48.5, 49, 51, 52, 55, 16/62;251/141, 138,140

[56] References Cited UNITED STATES'PATENTS 1,857,133 5/1932 Bommer 16/52 1,883,957 10/1932 Koch et al. 251/140 X 2/1946 Rice 251/138 X Hottenroth 251/138 2,644,662 7/1953' Powers 251/141 X 2,818,915 7 H1958 Pfeiffer 251/141 2,909,801 10/1959 Ellis et a1... 16/62 3,120,943 2/1964 Donelan 251/141 X 3,178,151 4/1965 Caldwell.... 251/141 X 3,420,496 l/1969 Hallberg 251/141 3,446,474 5/1969 Diver 251/141 3,546,734 12/1970 Pollack et al.. 16/62 3,593,241 7/1971 Ludwig 251/141 X 3,696,462 10/1972 Martin 16/55 X PrimaryExaminer- Roy D. Frazier Assistant Examiner-Peter A. Aschenbrenner [57] ABSTRACT An attachment for a conventional, surface mounted, overhead door control incorporating electrically actu ated provision for holding the door open to any desired degree, but defeatable by manual pressure or by deenergization of the electric circuitry.

9 Claims, 6 Drawing Figures 7 I 1' DOOR HOLD OPEN ATTACHMENT FOR A DOOR CHECK SUMMARY OF THE INVENTION In application Ser. No. 105,331, filed Jan. ll, 1971,

of Paul W. Martin for a COMBINED DOOR CHECK- ING AND DOOR HOLD OPEN MECHANISM,

there is shown a surface mounted door check unit of the type wherein arcuate movement of an arm rotates a pinion meshed with a rack carried by a piston. Rack movement compresses a spring upon door opening, and

the return thrust of the spring closes the door. The closthe passage and thus effectively prevented the further travelof the piston in the closing direction.

In surface mounted door closers of the type shown in the Martin application, it is conventional to provide two ports in the cylinder wall in the direction of travel of the piston in the closing direction and one port in the opening direction for the metered restraint on the piston, to or past which the piston must move. For the Martin device to operate effectively, the piston must make a fluid tight seal with the wall of the cylinder, thus demanding ring seals. As the sealing rings come to or pass the open ports, they necessarily will bulge into the ports, and as they return to the continuous wall portion, theystand a good chance of being scuffed or nibbled off. The scaling is not essential in the absence of the door hold-open provision of the Martin application, or in the other words, where the closer is to function simply as a door check, but it is needed where a fluid must be positively held ahead of the piston.

The device of the present invention contemplates a displacement of the door holding mechanism entirely away from the area of the fluid escape ports such that no sealing of the rack piston is necessary, and the movable member of the holding mechanism is not called on to pass any ports.

The device of the present invention contemplates a wholly enclosed valve operating armature such that no packing gland and no possibility of oil drip occurs at the site of the door holding valve.

The device of the present invention can be employed strictly as an accessory or an attachment to a standard door closer such that the standard closer may be modi-. fled simplyby substituting the door holdingmechanism for the conventional end plug with no further modification necessary. The door holding mechanism constitutes an axial extension of the door check and lies wholly within the longitudinal projection of the walls of the door check such that no mounting change need be made in the check upon incorporation of the door holding mechanism, and paneling or fairing may be employed to provide a surface continuous with that of the check proper.

Finally, the device of the Martin application shows a door hold-open mechanism which can be overpowered by manual pressure on the door wherein the door will stand open at the point where the overpowering force is released. The device of the present invention contemplates an optional structure where, upon the application of overpowering pressure even momentarily, the

.30 and 32. The inside detention of the door is released and the to closure.

Other objects and features of this invention will be apparent from the following description and drawings.

oor swings BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a horizontal section through a representative door checkincorporating the device of the present invention, shown in its condition when the door it controls'is fully open;

FIG. 2 is a similar section shown with the parts thereof in the door-closed position;

FIG. 3 is a fragmentary vertical section through the central portion of the check taken substantially along the line 33 of FIG. 1 looking in the direction of the arrows shown, however, without the device of the present invention;

FIG. 4 is a transverse section through the cylinder or housing taken along the line 4 4 of FIG. 1 looking in the direction of the arrows; I

FIG. 5-is a vertical section through an optional form of manifold; and

FIG. 6 is a horizontal section through the manifold of FIG. 5 taken along the line 6-6 of FIG. 5 looking in the direction of the arrows.

DESCRIPTION OF THE PREFERRED EMBODIMENT The left hand portion of FIG. 1 illustrates a conventional door check 10 of the surface mounted type. The door check (FIG. 3) may be mounted by screws 11 to a wall 13 immediately above a doorway with the operating end 12 of a pinion shaft 14 extending downward from the door check housing 15. An appropriate arm linkage 17 .will be clamped atone end to the operating end 12 of the shaft 14 and slidably engaged at its other end in a track 19 secured by screws 21 to the door 23 such that as the door is opened, the pinion shaft 14 will be rotated in one direction and as the door closes, it will be rotated back to the starting position. Such interconnection between the door check and the door is entirely conventional.

The housing 15 is internally longitudinally bored to define a cylinder 16. The pinion shaft 14 spans the cylinder 16 and is mounted in appropriate pinion bearings 18 with appropriate seals on opposite sides of the cylinder. The pinion shaft has an integral pinion 20 formed thereon within the cylinder 16. The pinion 20 engages a rack piston 22 within the cylinder. The rack piston may best be regarded as an elongated cylindrical member having a long transverse aperture 24 formed therein to leave cylindrical ends or heads 26 and'28 connected by opposite, longitudinally extending webs surface of web 32 has teeth formed thereon to define the rack 34 with which the pinion 20 engages. I

The left end of the-cylinder l6 asseen in FIGS. 1 and 2 is closed by a plug 36 secured within the open end of the cylinder in fluid-tight relationship, and a dorm closing, strong, compression spring 38 is contained bedirection, thus advancing the rack piston 22 to the left and compressing the spring 38 (FIG. 1). When the door is released, the pressure of the spring on the rack piston moves the piston to the right thus rotating the pinion in a counterclockwise direction and through the linkage with the door, draws the door shut.

The rack piston has one way, axial, fluid flow passages 40 and 42 through the heads 26 and 28, respectively, controlled by ball check valves 44 and 45 to forbid fluid flow from the faces of the rack piston heads into the central slot 24 but to permit flow from the central slot out the ends of the piston. 8

As particularly illustrated in FIG. 3, the top wall 43 I of the housing is of augmented thickness to accommodate check flow passages. On the left side of the pinion 20, there is a back check system 48 which retards the movement of the door as it approaches its full open position. It includes a bore 50 extending perpendicularly through the wall 46 and opening into a shallow recess or groove 52 formed in the interior wall of the cylinder 16. A second perpendicular bore more remote from the pinion likewise extendsthrough the wall 46 which is formed and tapped for the reception of a needle valve 56. This bore opens into the cylinder at the intended end of'travel of the face of the cylindrical portion 26 of the rack piston in the door opening direction. An intersecting bore 58 interconnects the passage 50 and the needle valve seat 54. The bores 50 and 58 are plugged at their outer ends by plugs 60.

On the other side of the pinion 20 are the check passages operative as the door closes. Nearest the pinion 20 is a bore 62 extending through the wall 46 into the cylinder and opening into the recess 52 in the interior cylinder wall. The recess extends between and includes the opening ports of bores 50' and 62. Bore 62 is conformed and tapped for the reception of a rapid close needle valve 66. ,A plain bore 68 extends through wall 46 to the right of needle valve 66 and is plugged 60 at its outer end. Still further to the right is a bore 70 formed for the reception of a final, slow-close needle valve 72. An interconnecting passage 74 is provided in through the end 76 of the cylinder housing 15 to interconnect the bores 62, 68 and 70 and is plugged 60 at its outer end. Needle valve 66 is adjusted to provide a relatively free flow of hydraulic fluid and needle valve 72 to provide a highly restricted flow; I

For ease of understanding, the checkflow passages and the groove 52 have been shown in FIG. 3 as being situated on the vertical axis of'the cylinder 16, whereas, actually, the passages are offset from the axis and the groove 52 is in the upper left quadrant of the cylinder as shown in FIG 4 so that the groove 52 avoids the bearing structure 18 of the pinion shaft 14.

The housing 15 is provided at its righthand end with an internally threaded plug seat 78, and when the door check is employed solely as a dooropening and closingrate controller, such a plug will be emplaced. In the drawings here, the plug has been replaced by the door hold-open mechanism to which this invention is primarily directed, but it is believed important that the op eration of the door check itself by understood before embarking on a description of the hold open mechanism. Accordingly, let a simple plug be visualized as occupying the plug seat 78. The cylinder will be filled I with hydraulic fluid.

As the door moves from the illustrated open position of FIG. 1 to the illustrated closed position of FIG. 2

under the force of the closing spring 38, the rack piston 22 is forced to the right. At the start, the face of the right hand head 28 is approximately aligned with the rapid close needle valve port 62. As the face of the cylinder advances, the ball check valve 5 closes, compelling fliud flow through the ducts 62, 68, 70 and 74. Initial flow occurs through both duct 70 and duct 68 into the connecting duct 74, is restricted in exhaust by the needle valve 66 and bypasses the cylinder head 28 through the groove 52 into the central cavity 24 of the piston whence it escapes through the ball check valve 44 in the left hand piston head 26. This displacement continues until the head 28 covers the duct 68 whereafter flow occurs only through the tightly restricted needle valve 72. Movement thus continues at a greatly reduced rate dictated by the needle valve 72 until the door seats. It will be appreciated that although the spacing 'of ports 68 and 70 appears large, the geometry of the connecting arm is such that this piston travel represents only the last few degrees of the door swing.

In the opening direction, as the piston is moved to the left, the ball check valve 44 in head 26 closes, compelling fluid flow past the head and into the piston cavity 24 through the groove 52 until the head 26 passes the end of the groove and fluid flow must continue through needle valve 54, and ducts 58 and 50 to the groove 52. The restraint imposed here is to cushion the linkage as the door approaches its fully open position.

In the present invention, a door hold assembly 80 is threaded into the right hand end plug seat 78 instead of the imagined plug. The door hold assembly 80 includes a tubular shell 82 externally threaded at both its ends, one end being secured within the plug seat 78 and the other end 84 having mounted thereto a tubular solenoid shell 86, the solenoid shell being internally threaded to cooperate with the external threads at the end 84. The shell 82 slidably contains a double walled, annular, cup-shaped, door hold piston 88 having an axial through passage 90, an inner wall 92, a base 94 confronting the rack piston 22 and an outer wall 96, all

' of which define therewithin an annular cavity 98. The

base 94 of the piston has a bore through the bottom thereof stepping to a smaller diameter as at 102 which communicates with the annular cavity 98. A check valve ball 104 is contained in the bore 100 between a ball check valve seat 106 press-fitted into the end of the bore and retained by ball-check valve seat retainer 108, and a spring 110 biasingthe check valve ball toward closure. The piston is sealed against the inside wall of the shell 82 by a quad ring seal 112 contained in an appropriate circumferential groove in the outside surface of the piston adjacent its open end.

A cylindrical manifold 114 is contained within the outer end of the shell 82. Its inside face 116 has an annular groove 11-8 and an axial bore 120 extending only a short distance into the manifold. The groove 118 has a sleeve 122 press-fitted into the outer circumference thereof which extends deep into the annular cavity 98- closing spring 38 such that it exerts no perceptible effect on the door closing operation but ensures that the piston 88 will follow the rack piston 22 in its movement. The diameter of the sleeve 122 is appreciably less than the outside wall of the cavity 98 such that fluid may freely pass between the sleeve and that wall.

The axial bore 120 has a fluid return sleeve 126 press-fitted into it to extend into the axial passage 90 of the piston 88 in fluid tight relationship. The seal is effected by a quad ring seal 128 contained in an enlargement 130 of the passage 90 at its end remote from the rack piston and secured therein by a backup 132.

. The length of the sleeve 126 is such as to maintain its fluid-tight communicating relationship with the passage 90 throughout the range of movement of the piston 88.

v The manifold has three annular grooves in the cylindrical periphery thereof, two of them 134, for sealing rings 136 and a central manifold groove 138 serving as a departure point for forming certain internal passages. Reverting for the moment to the inside face 116 of the manifold, a blind hole 140 extends longitudinally into the manifold from the spring seat groove .118. A radial intersecting bore 142 is formed from the groove 138 through the inside end of the bore 140 to the center of the manifold. The axial fluid return bore 120 .stops short of the position occupied by bore 142 so asto isolate these bores from each other. A passage 144 angles inwardly from the groove 138 to intersect the inside end of the axial bore 120. A second passage 146 angles outwardly from the groove 138 toward the center line of the manifold. Although passages 144 and 146 are shown intersecting for reasons of clarity, the groove 138makes possible different points of entry of those passages thereinto. Adjacent its outer face 148, the manifold has a circumferential rib 150 thereabout.

The outer face 148 of the manifold has an annular groove 152 therein to receive a sealing ring 154, and inwardly of the groove, an annular nipple 156. Centered in the nipple is an axial plunger chamber 158 proportioned to accommodate loosely a plunger 160. The plunger is a generally cylindrical body a little longer than the chamber 158 with a tapering inner end 162 socketed to accommodate'a valve ball 164. Extending axially from the bottom of the plunger chamber 158 is a bore 166 which intersects bore 142. The shoulder 168 at which bore 166 meets the floor of the plunger chamberv 158 constitutes a seat for the ball 164.

A solenoidcap 170 consisting of a one piece, deeply drawn cup or thimble with a flange 172 about its mouth is contained against the outer face 148 of the manifold. The interior of the cup flts closely on the nipple 156 of the manifold andthe flange 172 thereof is of the same diameter as the flanged outer face of the manifold. The interior of the solenoid shell 86 has a rib 174 thereabout, and as the solenoid shell is threaded on the outer end of the piston shell 82, the rib 150 of the manifold and the flange 172 of the cup are caught between the end 176 of the solenoid shell 82 and the rib 174 to make, with the sealing rings 154 and 136, a fluid-tight end for the assembly. I

In the annular space between the wall 180 of the cup and the outward extension 182 of the solenoid shell 80 is located a solenoid winding 184, and an armature 186 is'situated within the cup in a position to be moved upon energization of the solenoid winding. The solenoid winding is contained in position by an annular sobefore, discharging fluid into the vacated space behind it through the ball valve 44 in the piston head 28. The door hold piston 88 will follow the rack piston in its movement under influence of the spring 124, the ball I check valve 104 yieldingto admit fluid therethrough into the annular cavity 98 and thence around the loose fitting sleeve 122 into the space vacated by the door hold piston 88.

Assuming now movement of the door from the open position to the closed position or from the condition of FIG. 1 to that of FIG. 2, the spring 38 expands moving the rack piston to the right which in turn forces the door hold piston to the right before it against the force of the spring 124. The ball check valve 104 closes and the fluid contained to the right of the door hold piston is forced around the spring retainer sleeve 122 into the space occupiedby the follower spring 124 and into the passages 140, 142, and 166 to the solenoid valve seat 168. If the solenoid is deenergi'zed, the solenoid valve ball 164 is displaced from the seat by fluid pressure, and fluid flow continues through passages 146 and 144 to the fluid return sleeve 126, through the door hold piston, and to the advancing face of the head 28 of the rack piston 22. Thereafter, the fluid bypasses that head as described in conjunction with the door checkmechanism proper.

Energization of the solenoid 184 will cause the armature to bear on the plunger 160 to hold the ball 164 against its seat and so prevent the passage of the hydrualic fluid from the right side of the door hold piston and thus maintain the door in an open'position. Even when the plunger is closed on the seat 168, it holds the armature away from the center of the solenoid field, so positive closing force exists. It will be appreciated that'the door need not be open to a fully open position for this retention to be effective. lf'the solenoid 184 is energized, the door will hold at any partially open degree to which it may have been moved.

The force withwhich the door is held open is mea- 'sured by the magnetic thrust of the armature 186 acting on the valve ball 164 against its seat. Desirably the solenoid will be so selected that this force will be specifi-' cally limited. lnother words, it is desirable that the solenoid be capable of being manually overpowered.

When the necessary excess of pressure is applied to the door to close. it, the generation of excess pressure within the chamber to the right of the door hold piston and within the space occupied by the spring 124 and transmitted to the ball 164 through the passages 140,

r 142 and 166 will lift the plunger off its seat and thus permit fluid flow past the valve in the fashion just described to permit a manual closing of the door.

The above described advantages of this structure will be appreciated from the description of the device thus far. The rack piston 22 which operates in the area of the fluid escape ports by whichthe rate of closure is governed has not and need not have anything in the way of deformable sealingrings whichmight be damaged by their passage to and through the ports. The door holding structure which does demandsuch rings is wholly displaced from the area of these ports and can operate within a continuous, smooth, cylinder surface. Likewise, there is a total avoidance of any exterior sealing of moving parts such as about the solenoid con-' trolled valve 160 through which leakage and drip might occur. It will be noted that the valve plunger 160 and the armature 186 fit relatively loosely within their associated containers. Hydraulic fluid may and will leak past the valve member 160 and the armature 186 into the cup 170, but such presence of fluid is wholly contained by static seals.

The door holding device is accessory in nature and may be incorporated into an existing closure simply by removing an end plug and substituting the device for it. The device lies within the longitudinally projected walls of the door check proper and lends itself to a masking by panels continuous with the side walls of the door check such that the only visible decorative consequence of its incorporation is an elongation of the unit.

In the device as just described, it will be appreciated that while the solenoid controlled ball valve can be overpowered 'to permit a forced closing of the door, once the application of overpowering force is halted, the ball valve will reclose and further movement of the door will stop. In the modification illustrated in FIGS. and 6, a manual release valving arrangement is shown whereby, once the valve is displaced from its seat by overpowering pressure, the valve will hold open until the door goes fully closed. The manifold 200 is very similar in exterior contour to the manifold '114 of the first described form. Thus, it possesses an annular groove 118 in its inside face to receive the sleeve 122 and an axial blind bore 120 to receive the fluid return sleeve 126. On its cylindrical periphery it has the two sealing grooves l34the central manifolding groove 138 and, at its outer face, the shoulder 150 to be clamped between the end of piston shell 82 and the flange 172 of the cup 170 by the solenoid shell 86. In its outer face, it has the annular sealing groove 152 and the tubular nipple 156 in which the plunger chamber 206 is formed. To this extent the two manifolds are essentially identical.

The points of difference between this manifold and 'the first described form lie essentially in the use of a difoutwardly of bore 220 as at 226. These passages may be collectively referred to as the inlet passage 227 to the solenoid valve.

The exhaust passage 230, 230a differs from the first described form. The immediate point of exhaust from the ball valve plunger chamber, instead of being situated immediately adjacent the ball valve seat 218, is

displaced substantially outwardly of the ball valve seat in reference to the axial length of the plunger chamber as at bore 232 in the side wall thereof. This outward displacement is such that when the ball 208 of the plunger 202 is seated against the ball seat 218, the

plunger head 216 will cover the exhaust port 232. A bore 234 extends parallel to the axis of the manifold ferent valve body or plunger202 and a differently situated exhaust port 204 from the plunger chamber206.

In this instance the plunger 202 mounts a valve checkball 208, as before, at its tapered inner end 210 which diverges to a cylindrical portion 2l2.which stands well clear of the walls of the'valve chamber 206 so as to permit a free flow of fluid therepast. Outwardly of the portion 212 the plunger is necked down as at 214 and then expands again to a plunger-head 216 which fits as.

closely within the walls of the plunger chamber as conventional machining practices conveniently permit and extends outwardly at this diameter to the outer end which is engaged by the solenoid armature 186.

The admission of oil from the space back ofthe door hold piston 94 to the ball valve seat 218 is as described before. A bore 220 extends from the annular groove 118 to intersect a radial bore 222 extending from the manifold groove 138 through the center of the manifold 200 which in turn is intersected by a small diameter bore 224 extending from the plunger chamber 206 to the radial bore 222. The radial bore 222 is plugged 200, intersecting the exhaust port 232 and going to a point radially aligned with the manifold groove 138. A hole 236 extends radially from the groove to intersect the bore 234. Thus a passage is completed to the manifold groove 138 through 236, 234 and the exhaust port 232. The bore 232 at its outer end forms only a groove 238 in the wall of the nipple 156, but the side wall 180 and flange 172 of the cup 170 enclose the groove to make a closed passage of it.

At another point in the manifold groove 138, here shown to be opposite, another bore 240 extends from the ring to the central fluid return tube 126 to'constitute the leg 230 of the fluid exhaust passage, as in the principal described form.

Parenthetically, it should be noted that FIGS. 5 and 6 show two planes through-the manifold whereas FIGS. 1 and 2 show only a single plane in order to make more clear the relationship of the parts. Actually, the fluid inlet 140, 132, 166 and the two legs 146 and 144 of the fluid outlet need not all be situated in the same plane as shown in FIGS.'1 and 2. Thus, the passage 144 of FIGS. 1 and 2 could occupy the same diametrically .op-

ter of convenience of machining.

The operation of this alternative form of-manifold is as follows. Assuming the door hold-open piston is in the open door position as illustrated in FIG. 1 with a quantity of fluid contained in the cavity behind it'communieating through the solenoid valve inlet duct 227,to the valve seat 218, and the solenoid 184 is energized, the door will be held open by virtue of the obstructed flow through the valve seat 218. As manual pressure is now applied to the door in the closing direction sufficient to overcome the thrustof the solenoid armature 186, the ball is displaced from the seat 218'and the pressure of the fluid as generated by the closing spring 38 will be applied against the entire face of the plunger including the head 216. Since the force is now acting on a greatly increased surface, the counter pressure exerted by the fluid against the solenoid armature will be greatly augmented. The proportioning of the solenoid thrust, the return spring pressure, and the whole face surface of the plunger head 216 is such that'the pressure-of the spring 38 acting on the plunger face is'sufficient to conuntil the door has reached full closure. At this point, the pressure on the plunger drops and the force of the solenoid armature is again sufficient to restore the ball to closure on the seat 218. In summary, therefore, with the solenoid energized, as one opens the door, the movement is easy and the door remains at the position to which it was opened. Upon the application, then, of excess closing force to the door through just enough arc to unseat the ball 208 from its seat 218, the door will swing to closure without further application of force.

Since the plunger 202 fits the chamber 206 in near fluid-tight relationship in this modification, means must be provided for supplying fluid to or exhausting fluid from the outer end of the plunger as contained in the cap 170. That part 242 of groove 238 outwardly of the plunger chamber exhaust port 232, walled in by the cap 170 is in open communication with the interior of the cap, connecting it to the zero pressure exhaust side of the solenoid valve, so fluid is free to move back and forth. The armature in this embodiment is loose within the cap as in the first described form.

It is not essential that the plunger 202 be fluid-tight within the chamber since the back side of the plunger is at zero pressure as long as the fit is close enough to hold the leakage level well below the input capacity of the inlet system to and through the solenoid valve. Given the viscosity of the hydraulic fluid, this is easily achieved by simple machining, and so again, sealing rings are avoided.

I claim:

1. in a door check of the type which includes means defining a cylinder, a member slidable within said cylinder, resilient means biasing said member toward one end of said cylinder, means for connecting said door check to a door and frame combination to move said member relative to said cylinder against said biasing means upon opening said door, hydraulic fluid in said cylinder and means for permitting fluid flow counter to the movement of said member to restrain the movement of said door; a door hold-open mechanism comprising means providing an extension of said cylinder on that end thereof toward which said member is biased, a piston resiliently biased Within said extension to follow said member and having a one way flow passage therein to admit fluid therethrough upon following movement against said resilient means, means closing said extension, said closing means including a passage having a valve seat therein for delivering fluid from the downstream side of said one way flow passage to the upstream side thereof, a valve for closing against said valve seat, and electrically actuated means for operating said valve.

2. The combination of claim 1 wherein said valve closes against said seat from the downstream side thereof.

3. The combination of claim 1 wherein said valve is energized with sufficient force to close against the pressure imposed by said resilient means but insufficient force to hold against a pressure in excess of that of said resilient means.

4. The combination of claim 2 wherein said valve is energized with sufficient force to close against the pressure imposed by said resilient means but insufficient force to hold against a pressure in excess of that of said resilient means.

5. The combination of claim 1 wherein said resilient means establishes a pressure on the fluid between said piston and said closing means, said valve has a face larger than said seat and said fluid delivery passage includes a valve chamber on the downstream side of said valve seat containing closely said valve, and said elecon said seat and including additionally a thimble mounted in fluid-tight relationship to said cylinder defining means and containing the end of said valve assembly remote from said face, and magnetic valve operating means on the exterior of said thimble;

7. The combination of claim 1 wherein said fluid delivery passage includes a tube mounted in said closing means and extending through said piston throughout the range of movement thereof.

8. A combined door check and door hold open device including resilient means for urging a door toward closure upon expansion thereof,

means defining a hydraulic cylinder, a piston therein connected to move toward one end of said cylinder with the expansion of said resilient means, said resilient means establishing a pressure per unit I area on fluid ahead of said piston, means associated with said one end of said cylinder defining a passage for the escape of fluid from said one end having a valve seat therein, a valve adapted to. close against said valve seat from the downstream side thereof, said valve having a face larger than said valve seat, a valve chamber downstream of said seat, a portion of said valve downstream of said face closely contained in said chamber to substantially prevent fluid flow past said valve and allow a pressure drop across said valve when'said valve is open, means providing a fluid escape passage opening into said valve chamber upstream of said valve face at an open position of said valve, means providing a fluid escape passage from said valve chamber behind said closely contained portion of said valve when in said open position, and means adapted to hold said valve resiliently against said seat with a force in excess of the product of said pressure and said valve seat area and less than the product of said pressure and said face area. 9.,The combination of claim 8 wherein said means for resiliently holding said valve are electrically operated. 

1. In a door check of the type which includes means defining a cylinder, a member slidable within said cylinder, resilient means biasing said member toward one end of said cylinder, means for connecting said door check to a door and frame combination to move said member relative to said cylinder against said biasing means upon opening said door, hydraulic fluid in said cylinder and means for permitting fluid flow counter to the movement of said member to restrain the movement of said door; a door holdopen mechanism comprising means providing an extension of said cylinder on that end thereof toward which said member is biased, a piston resiliently biased within said extension to follow said member and having a one way flow passage therein to admit fluid therethrough upon following movement against said resilient means, means closing said extension, said closing means including a passage having a valve seat therein for delivering fluid from the downstream side of said one way flow passage to the upstream side thereof, a valve for closing against said valve seat, and electrically actuated means for operating said valve.
 2. The combination of claim 1 wherein said valve closes against said seat from the downstream side thereof.
 3. The combination of claim 1 wherein said valve is energized with sufficient force to close against the pressure imposed by said resilient means but insufficient force to hold against a pressure in excess of that of said resilient means.
 4. The combiNation of claim 2 wherein said valve is energized with sufficient force to close against the pressure imposed by said resilient means but insufficient force to hold against a pressure in excess of that of said resilient means.
 5. The combination of claim 1 wherein said resilient means establishes a pressure on the fluid between said piston and said closing means, said valve has a face larger than said seat and said fluid delivery passage includes a valve chamber on the downstream side of said valve seat containing closely said valve, and said electrically actuated means is adapted to urge said valve against said seat with a force greater than the product of the pressure of said resilient means and the area of said valve seat and less than the product of the pressure of said resilient means and said valve face.
 6. The combination of claim 1 wherein said valve is an elongated assembly having a face adapted to close on said seat and including additionally a thimble mounted in fluid-tight relationship to said cylinder defining means and containing the end of said valve assembly remote from said face, and magnetic valve operating means on the exterior of said thimble.
 7. The combination of claim 1 wherein said fluid delivery passage includes a tube mounted in said closing means and extending through said piston throughout the range of movement thereof.
 8. A combined door check and door hold open device including resilient means for urging a door toward closure upon expansion thereof, means defining a hydraulic cylinder, a piston therein connected to move toward one end of said cylinder with the expansion of said resilient means, said resilient means establishing a pressure per unit area on fluid ahead of said piston, means associated with said one end of said cylinder defining a passage for the escape of fluid from said one end having a valve seat therein, a valve adapted to close against said valve seat from the downstream side thereof, said valve having a face larger than said valve seat, a valve chamber downstream of said seat, a portion of said valve downstream of said face closely contained in said chamber to substantially prevent fluid flow past said valve and allow a pressure drop across said valve when said valve is open, means providing a fluid escape passage opening into said valve chamber upstream of said valve face at an open position of said valve, means providing a fluid escape passage from said valve chamber behind said closely contained portion of said valve when in said open position, and means adapted to hold said valve resiliently against said seat with a force in excess of the product of said pressure and said valve seat area and less than the product of said pressure and said face area.
 9. The combination of claim 8 wherein said means for resiliently holding said valve are electrically operated. 